Mars is a dry planet, probably covered with sandy stretches of desert. Venus may or may not be covered with watery seas. We do not know because our telescopes cannot pierce the dense veils of atmosphere above our sister planet. The other planets have little or no water, even in their atmospheres.
So far as we know, our seas are the only stretches of water in the Solar System. If there are intelligent beings on the other planets, they probably have named our earth the World of Water. We are used to life on the dry land and tend to forget that almost three quarters of our big globe is covered by water   salt water and fresh water.
The total area of the earth's surface is about 197 million square miles. A little more than 54 million square miles of this area pokes above sea level and about 14.3 million square miles is under water. The dry land covers only about three tenths of the earths s surface.
In area, then, the stretches of water are far larger than the area of dry land. But in bulk, the difference is even more startling. Let's compare the volume of the earths water with the volume of land above sea level. The land, of course, is full of ups and down  . but let's use an imaginary bull dozer to make it all level. Now lets take our bull dozer and level off the floors of the seas.
 The flat land areas would all stand more than a mile above sea level. The flat floor of the sea would be more than five miles deep. In bulk, or volume, the earths water is 13 times greater than the dry land above sea level. We do, indeed, live on a watery world.
Most of the water is held in the five deep ocean basins blow the Atlantic, Pacific, Indian, Arctic and Antartic Oceans. The waters of these oceans are linked together on one vast world ocean. They also connect with the Mediterranean, the Baltic and countless other small salt water seas.
Then there is the fresh water in big and little lakes, in running rivers and lazy creeks. As we travel over the land, there seems to be a great deal of this fresh water. But compared with the vast area covered by the seas, it counts for almost nothing at all, It is not enough to change the estimate that only three tenths of the world is above water.
 We may not be aware of our vast water supplies all the time. But nevertheless, the oceans which enfold the surface of our planet play a great role in our daily lives. Most important, they surely have most of the moisture to make the rain which falls upon the dry land.